Maybe just cut the bms out and monitor urself? Confirm it even is the bms
yep, did that- It is definitely the BMS.
I don’t have a 10s balance charger, and really liked the extra BMS functionality since I could use a laptop style charger with zero worries… might just have to get a new BMS at some point
Dangit… I have the same BMS and I think I am experiencing the same issue.
Mine cuts off after awhile too. While riding, it just cuts off. I turn it on and then back, and it just works and dies soon after… No idea.
I also had some kinda of smoke coming from the BMS unit.
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currently using no bms and just an imx b6 with low speeds when riding and a voltage alarm
You have the same BMS as us?
yea it was the back up I used after the tb stopped working but it has the exact same issues as yours
crap, seems more common than I thought…
time to re think the charging setup.
Bulk charging and ten dollar monitor/balancers is so simple. Less things to break. Charge at 400 watts and not have to disconnect batteries just use the single battery plug with them all in series.
I heard that these BMSes were “frying” but I found no evidence or posts about them. I guess those were true. I want to do more testing to make sure that this thing is chopped.
I guess the best test would be to run directly without a BMS connected… Here goes nothing.
I’ve been doing bench testing…
So after fully charging my battery to 43.2v(charge voltage), I turned on my soft switch and let the receiver and ESC turn on. I did not run the motor. After about 5-10 minutes the voltage dropped to almost nominal voltage. At around 41v or so, the ESC and receiver just shut off for no reason.
The battery definitely has charge left. I’ve drained it to 36v and it usually dies around then.
Do you have this similar issue? I’ve also inspected the PCB and I can’t see any issues. Most of the components are within the two stacks so it’s hard to tell.
yep, similiar issue.
I had my battery fully charged, and the VESC’s would still just turn off (lights would go out) for no reason.
On the bench it would take longer than if I flipped over the board and attempted to ride it: if I rode it, the BMS cut power almost immediately…
This is super weird.
The first time after modifying the setup and discovering the issue, I probably rode 1/2 a mile before the BMS cut off and launched me into thin air… That seems to be longer than what it is now… can’t figure out why.
I am fairly certain that the BMS is falsely detecting a low voltage cell or something and shutting off. Even my battery gauge meter will shut off after awhile.
Also to note, everytime I turn on the softswitch, the power goes through the system and then cuts as if the BMS is detecting then cutting load.
Time to make Raphael Chang’s BMS.
Ya I have no clue what’s happening.
First started on the way home from a 12 mile ride- cut out with about 3 miles to go. But I just flipped the soft switch on/off and the board started running fine again. Although it cut out more and more as I got closer to home on the ride.
Thought it was heat, but when I came back the next day it still was happening, and even worse.
Charged the battery, same problem still.
Now she’s been torn apart for the last month or so looking very depressed 
If you do end up making a BMSaturday, I would gladly pay for you to make a second for me 
This part of your problem could be something to do with the current draw at a lower voltage which would make the voltage sag to cutoff discharge voltage.
My build has been sitting for a few weeks too 
If I build his BMS, I will probably make a few after testing first. Even if something goes wrong on his BMS, at least there is a way to figure out what is going wrong. His will probably cost around $90-$100 each without being mass produced btw.
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So I disconnected and reconnected the ESC and balance connectors to the BMS and now it does not shut off. My battery seems to be fine and the BMS is not shutting it off.
I’m sure it will come back though. Maybe I should let the cells balance charge for awhile… The BMS will cut load if a cell drops below a certain voltage… My cells were unbalanced a tad bit.
After test riding it today and I’ll see if I’ll remove the BMS or not.
huh… strange…
I’ll go through my setup at some point… this weekend is crazy with Florida Georgia tomorrow (huge rival football game here in Jax), and my recent aquisition of a 1949 jeep willys cj3a.
Haha nice buy Those things are so cool.
nearly as fun and equally scary as riding an eboard.
The manual steering on that thing has so much play it doesn’t like going more than 35mph.
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Currently doing an autopsy… Sorry to hijack this thread so much but I don’t think it’s worth making a new one for. Let me know if you’d rather me make a new thread.
Found a short between the balance connectors… Could this be causing all the issues?
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Yes that is a major issue